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U.S. NATIONAL MUSEUM BULLETIN 227 



rami; without hyaline glands. Gonads develop in both dorsal and 

 ventral rami. 



Biology. — The species has been studied in some detail by Southern 

 (1911), Huntsman (1921), and Bigelow (1928). Individuals fre- 

 quently appear in the Gulf of Maine, though never forming an im- 

 portant constituent, quantitatively speaking. Found chiefly outside 

 the outer islands and rarely in estuarine waters tributary to the Gulf 

 of Maine. Taken in every month of the year with no definite fluc- 

 tuation in abundance from season to season, from the surface to 100 

 fathoms, migrating daily and coming to the surface most often at 

 night. Reproduces during the summer in the Gulf of Maine, re- 

 producing at least enough to maintain a rather sparse stock. Very 



Figure 24. — Tomopteridae, Tomopteris helgolandica, dorsal view (drawn from type of 



Tomopteris smithii Verrill). 



